The invention relates to a sterile container for medical purposes having a tub-shaped lower portion and a lid positionable thereon in sealing manner, which lid may be clamped against the lower portion by a lock, wherein the lock comprises a flap swivellable between an open position and a closed position, said flap having a locking projection, and a locking lug with a recess for accommodating the locking projection when the flap is in the closed position.
Such sterile containers are closed in sealed manner in that a resiliently deformable seal is arranged between lid and tub. If the lid is clamped against the tub, this seal is resiliently compressed and ensures that a reliable seal is established around the entire circumference. Clamping together is enable by a special closure, which, in the case of known sterile containers, comprises a flap mounted swivellably on one portion (lid or lower portion) and a locking lug fixed to the other portion. The entire locking lug is capable of resilient deformation, such that a locking projection on the flap engage in a locking recess in the locking lug when said flap swivels, the locking lug undergoing such resilient deformation upon said swivelling movement that the locking projection may slide into the locking recess. The clamping force required for clamping lid and lower portion together is supplied by the resilience of the locking lug.
Although this design has proven very convenient and is therefore also used very widely, certain difficulties do arise in compensating manufacturing tolerances and in establishing the necessary clamping force between lid and lower portion.
The object of the invention is to so develop a sterile container of the generic type that the design thereof allows better compensation of manufacturing tolerances and optionally also better adjustment of the clamping force between lid and lower portion.
This object is achieved according to the invention for a sterile container of the above-described type in that the locking projection in the flap may be displaced resiliently in a direction in which it is moved out of the recess in the locking lug.
With the new design, therefore, the locking projection in the flap is in turn of resiliently displaceable construction and, in accordance with the dimensions of the flap, a relatively large displacement path is available thereto which is as a rule substantially larger than the displacement path provided by a resiliently deformable locking lug. This extension of the displacement path eases adaptation to manufacturing tolerances and it is additionally possible to vary the spring fore with which the locking projection is displaced in the direction of the recess.
In principle, it is possible to make the locking projection in one piece with the flap, resilient deformability then being achieved in the resiliently deformable connecting members are arranged in the connecting area between locking projection and flap, for example spring-type webs or the like.
In a particularly preferred embodiment, however, provision is made for the locking projection to take the form of a locking member separate from the flap, which locking member is mounted in the flap so as to be displaceable in a guide. Such a construction has the advantage that it is particularly simple to produce and, in addition, different materials may be used, for example the locking projection may consist of a sterilisable plastics material while the flap consists of metal.
It is beneficial for the guide to be open at one end and closed at the other end. This makes it particularly easy to insert the locking member, which is simply introduced into the guide from the open side. This open end may preferably face the swivel axis of the flap.
A particularly easily produced guide takes the form of the edge strips of a cutout portion of the flap, which strips engage in lateral longitudinal channels in the locking member.
It is also advantageous for the locking member to be held captive in the guide by a limit stop which may be moved resiliently out of engagement when the locking member is introduced into the guide. In particular, such a limit stop may take the form of a resilient catch, which engages in a recess extending in parallel with the guide.
In this way, assembly is made particularly simple, it being sufficient to introduce the locking member into the guide from the open side, the limit stop being brought resiliently out of engagement until the locking member is introduced into the guide. Then the limit stop moves back into the rest position and from this moment prevents withdrawal of the locking member from the guide.
Spring means are preferably arranged between the locking member and the flap, which effect the resilient displacement of the locking member.
These may be conventional spring means, for example helical springs.
It is beneficial for the flap and/or the locking member to comprise a receiving space for the spring means, such that the latter are inserted only loosely between flap and locking member and are then held in the receiving space, additional retaining means then being superfluous.
In a particularly preferred embodiment, provision is made for the receiving space to be so dimensioned that it may accommodate as spring means several compression springs next to one another. This allows the resilient forces with which the locking member is displaced in the direction of the recess in the locking lug to be varied by the insertion of different numbers of such compression springs. In this way, the clamping forces exerted by such a closure may be adjusted, which is of great significance, since the clamping forces required for obtaining uniform deformation of the seal between lid and lower portion increase in proportion to the length of the seal, such that different clamping forces are required for different sizes of container. These forces may be easily adjusted by the number of compression springs selected and in this way the same closure design may be used for containers of different sizes. Through an appropriate choice of spring force, it is also possible to adapt the clamping force to special sealing characteristics of the seal, the clamping force of the compression springs being less for soft seals than for hard seals.
It is particularly advantageous if the spring means are pretensioned in the relaxed end position. Through appropriate selection of the spring characteristics of the compression springs, this allows a resilient restoring force to be generated which is substantially without variation over the entire displacement distance of the locking member, such that these restoring forces remain extensively the same even where dimensions vary for structural reasons.
A particularly space-saving and favourable design is obtained if the locking member is mounted so as to be displaceable in the plane of the flap in the direction of the swivel axis thereof.
The flap may be in particular of U-shaped construction, with two limbs which define the swivel axis at their free ends and with a central cutout which accommodates the locking member.
In principle, given the above-described design of the flap with a resiliently displaceable locking projection, it is not necessary for the locking lug in turn to be of resilient construction; however, a preferred embodiment provides for the locking lug to be of resilient construction in such a way that, when the flap swivels, it moves slightly to make way for the locking projection on the flap. This is particularly useful where it is desirable for the locking member to effect as slight as possible a displacement movement, for example for dimensional reasons, such that then both the locking lug and the locking projection assume responsibility for part of the resilient displacement of the closure parts.
The resilience of the closure parts may provide such a long-stroke construction that, even when the closure is in place, the lid may be moved far enough away from the tub-shaped lower portion against the resilient closing force of the closure that an opening is formed between lid and tub-shaped lower portion. This embodiment has the advantage that the lid may thereby be raised resiliently from the tub such that any excess pressure prevailing inside the latter may be released. Thus, if the resilient closing forces are selected appropriately, the removal of air from the container may be performed during the sterilisation process, for example, without its being necessary to provide the container with a separate outlet valve or a separate outlet opening for the air. In addition, in the after-drying stage, which takes the form of a vacuum stage in conventional steam sterilisers, lifting of the lid may serve to dry the container contents. The moisture-saturated atmosphere is extracted from inside the container through the opening produced between tub and lid.
Such a sterile container construction is particularly advantageous in the case of a closure construction as described here, i.e. in the case of a closure having a swivellable flap with locking projection and locking lug. In principle, however, such a construction may be used for all sterile containers in which the lid is pressed resiliently against the tub by a closure, irrespective of the particular construction of the closure. The only essential factor is that the closing force is applied resiliently over a relatively long displacement path, such that the stroke which the lid may effect against the resilience is long enough for the lid to be capable of being lifted from the tub. The stroke has optionally to be long enough to take account of the deformation of a resilient seal between lid and tub.
It is beneficial for the sterile container to be closed completely when the lid is positioned sealingly thereon and for the inside thereof to be connected with the surroundings only by means of an inlet valve, which may be spring-loaded. An outlet valve is no longer necessary in the event of such a design, however, since the function of the outlet valve is assumed by the resiliently raisable lid.
It may further provided that a lifting element is arranged on the lid, by means of which the lid may be moved away from the tub against the action of the resilient closing force of the closure when the latter is in place. This is significant when, for example during the drying stage, it is intended that lifting of the lid should be effected not only as a result of the excess pressure inside the container but also deliberately from outside, for example by means of a controlled lifting device.